Electron discharge device



Dec. 24, 1946. C. v. mwN 2,412,998

ELECTRON DISCHARGE DEVICE Filed Feb. 7. 1942 FIGA.

1 TTORNEY.

Patented Dec. 24, 1946 ELECTRN DISCHARGE DEVICE Charles V. Litton, Redwood City, Calif., assigner to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Aapplication February '7, 1942, Serial No. 429,872'

This invention relates to electron discharge devices and circuits and particularly to such arrangements adapted to operate at ultra-high frequencies.

The principal object is to improve the performance and power output at which such devices may be made to operate effectively at ultra-high frequencies.

This application is a continuation-in-part of my co-pending application Serial No. 334,535, filed May 11, 194i), patented as No. 2,372,213 March 27, 1945.

There have heretofore been used electron discharge devices having cavity resonator circuits tuned to ultra-high frequency resonance. As different operating voltages are ordinarily applied to different electrodes of such devices, it has been required that a cavity which is coupled between two electrodes and directly connected to one of them, should be coupled without any direct connection to the other, in order that the different electrode operating voltages may beV kept separate. The provision of an efficient low impedance coupling at ultra-high. frequency has been a diliicult problem owing to the small dimensions required of the conductingparts of the tube and the high D. C. voltage which the coupling inember must withstand.

In accordance with this invention, there is provided a low impedance coupling capacity arrangement within the vacuum for coupling a tube electrode with the cavity resonator. The provision of the capacity plates or surfaces within the vacuum facilitates the provision of a large coupling capacity, permitting the condenser armatures to be placed closer together for a given voltage than would be practical in the atmosphere. A feature is the utilization of the electrode surface itself, as an armature of the coupling capacity.

The invention will be understood from the following detailed description and the accompanying drawing, of which Fig. 1 illustrates an electron discharge device having a cavity resonator coupled to the control grid by a capacity coupling constructed in accordance with this invention; and

Fig. 2 illustrates another tube wherein the resonator is coupled to the anode by a capacity coupling according to this invention.

Fig. 1, which is the same as Fig. 3 of my said copending application, Serial No. 334,535, shows a cavity type resonator in the shape of a toroid I forming the larger portion of the envelope of a'vacuum tube. The toroid is closed near its 6 Claims. (Cl. Z50-27.5)

lower periphery by a cylindrical vitreous seal 8, and its upper periphery is closed by a circular metallic anode 2 which may be sealed and attached tothe toroidalperiphery as by brazing. The material of the metal I and 2- ispreferably copper. Just below the circular anode 2l is a contro-l grid 5, formed by an outer cylindrical wall 5a, an inner cylindrical wally 5b and a number of radial ns 5c attached between the inner andV outer cylinders to provide the desired grid construction. The grid is supportedy in position by the sealing of outer cylinder 5a into the glass seal 8.

The cathode 6, placed below the grid, is of the indirectly heated type, heated by a suitable heating element l, across which is connected a Voltage for producing the heat. The cathode is likewise supported by means of its outerl cylindrical wall 6a which is embedded in the seal 8; and the electron emitting surface is provided by the cylindrical portion Bb extending centrally across the cylinder ia.

The metallic toroidal resonator I, directly connected to the anode 2, is coupled to the grid to complete a resonant grid-anode circuit, by the lcylindrical extension of the toroid Ib into the evacuated vessel and closely surrounding the cylindrical member 5a of the control grid. The proximity of cylinders 5a and Ib produces a coupling capacity therebetween which is of a desired low impedance at ultra-high frequencies. By this arrangement, a high voltage can be connected to the anode and a diierent Voltage can be applied to the grid, as these two-electrodes are insulated from each other for direct current voltages even though they are eiTectively coupled together at ultra-high frequencies.

The output terminal for the tube I, Whether it is used as an oscillator or an amplifier, may be taken in a well-known manner, the means shown being the coaxial line formed by the looped wire I9 brought into the resonator and connected thereto, concentrically within the metallic cylinder Illa connected and sealed to an aperture in the resonator. To maintain the vacuum, the wire I0 and coaxial cylinder Illa are sealed by the vitreous seal II, which is sealed to the portion IIlb of the cylinder.

Fig. 2 shows another modiiication in which the coupling capacity is placed between the resonator and the anode, which enables the high'anode voltageto be kept off the resonator. In this arrangement, the resonator is likewise a toroid I, forming a wall of the evacuated vessel. There is attached as by brazing, to one periphery of the toroid, a cylindrical sleeve I5 to which is also attached a suitable metallic sealing member I6, also generally cylindrical in shape and extending coaxially with reference to cylinder I5. Cylinder I6 may have a threaded portion for attachment to a suitable socket or terminal, for example, to a concentric transmission line.

The anode l1 is in the form of an elongated cylinder I8, closed by a solid cylindrical portion I9 and having at its mouth a grid-like construction, somewhat similar to the grid 5 in Fig.`1. This grid-like construction comprises a ring 20 with a number of radial iins 2| extending from the ring to the peripheral mouth f the anode. By this arrangement substantially uniform anode potential is presented across a surface parallel to the cathode, but heat concentration that would occur with use of a plate surface is avoided. The end of the anode structure opposite the mouth is formed into a thin edge 22 for sealing to a vitreous section 23, which is bent back and sealed to member I6 to form part of the evacuated envelope. A length of tube 24 may be inserted concentrically within the outer elongated cylindrical anode portion and supported by an extension 25 of the anode by Webs or blocks 26. The inner end 21 of the tubing should be spaced somewhat from member I9 of the anode so that a cooling iiuid such as air may be passed through the inside tubing and around the outside thereof and through the spaces between supporting webs 26 in a continuous stream to cool the anode.

The control grid'5 is of the same general form as that shown in Fig. l, and is supported by attachment, as by brazing of its cylinder a to the periphery of the toroid remote from sleeve I5. There is attached to cylinder or sleeve 5a, a cylinder or sleeve 28, which may be provided with a threaded member 29 forattachment to a support or tube terminal. The opposite end of member 28 is sealed to a re-entrant vitreous section 3G, the inner pressed portion 3| of which supports three rods 32, 33 and 34, passing through it. The central rod 33 is a support and terminal for the indirectly heated cathode 35 having the cylindrical portion 36 crossed by the circular electron emitting section 3l. The other two rods 32 and 34 are terminals and supports for the cathode heating element 38.

As the outer cylindrical Awall of the anode is within and closely spaced from the inner cylindrical surface of sleeve i5 there is provided the desired coupling capacity between the cavity and the anode, so that the desired highfrequency resonant circuit is set up by reason of the direct connection of one periphery of the toroidal cavity to the grid and the capacity coupling of the other cavity periphery to the anode. This arrangement likewise has the advantage of placing the coupling capacity within the vacuum of the vessel. p,

The output of the tube may be taken at the concentric line l0 and lila, these portions being sealed by the vitreous sealing section 39. The input circuit could also be a toroid, or it might be a transmission line, located Aexternally of the tube and connected with the grid and cathode as its opposing terminating electrodes.

The constructions according to this invention, enabling the coupling capacity Vin the anodegrid resonant circuit to be placed within the vacuum of the vessel, results in an increased eiiiciency and output by reducing the voltage loss across this capacity and reducing the sparking which occurs less readilyin vacuum than in air; and this enables the condenser plates to be brought closer together than otherwise. The resultant increase of capacity contributes to the reduction of the voltage drop across it.

What iS claimed is:

1. A high frequency electron discharge tube including a conducting toroidal resonator having inner and outer cylinders, said inner cylinder having a gap intermediate its ends, an anode mounted Within said resonator and connected to said resonator on one side of said gap, and a cathode and a grid mounted within said resonator and sealed to said resonator on the opposite side of said gap and electrically insulated therefrom, said grid being positioned between said anode and said cathode and having a tubular extension extending away from said gap, the diameter of said extension being smaller than the inner diameter of said inner cylinder.

2. A high frequency electron discharge device including a conducting toroidal resonator having inner and outer cylinders, said inner cylinder having a gap intermediate its ends, an anode mounted within said resonator and connected to said inner cylinder on one side of said gap, a grid mounted within said resonator and insulatingly sealed to said inner cylinder on the other side of said gap and including a portion spaced from and substantially parallel to said inner cylinder to which said grid is sealed, and a cathode insulated from said resonator.

3. An ultra high frequency electron discharge device of the resonator type including a container having an outer cylindrical wall and reentrant portions at both ends thereof, a rst electrode mounted on one of said portions and insulated therefrom, a second electrode mounted on the other of said portions, and a conductive member also mounted on the same portion as said first electrode and being in substantial capacitive relation to the surface of said rlrst electrode.

4. The combination according to claim 3 in which the conductive member extends parallel to the surface of the anode, and in combination therewith means, connected with the reentrant portion which mounts the second electrode, supporting a cathode.

5. An electron discharge device adapted for ultra high frequency operation comprising an evacuated vessel having a resonator, said vessel containing a cathode, a control grid and an anode,

` said grid being coupled to one portion of said resonator and means coupling said anode to another portion of said resonator, said coupling means comprising means capacitatively coupling said resonator with the surface of said anode.

6. An electron discharge device adapted for ultra high Vfrequency operation comprising an evacuated vessel having a resonator, said vessel containing cathode, control grid and anode electrodes and a cylinder, said resonator being directly connected at one side to one of said electrodes and connected at its other side to said cylinder, another of said electrodes being mounted at the same side of said resonator as said cylinder but insulated therefrom and said cylinderv being mounted coaxially vand capacitatively coupled with respect to the surface of saidv other electrode.

' CHARLES V. LITTON. 

